The present invention relates to methods and machines for the release and separation of foreign matter from fibers such as cotton. The invention is applicable to two distinct purposes: (1) providing apparatus for precise and accurate laboratory measurement of foreign matter in fiber; and (2) providing apparatus applicable to high production rate fiber processing machinery.
Increasing demands are being placed on fiber properties as textile processing machinery production rates increase and as the tolerances of textile processing machinery for variances in the fiber properties decrease. Current production and harvesting methods inherently entrain more foreign matter content into cotton fiber, for example, such that the ginning and cleaning actions required to achieve a given percentage of foreign matter content are increasing. Increased cleaning is always at the expense of fiber loss and damage. The incompatibility between the goals of clean versus undamaged fiber increases the difficulties faced by producer, ginner, buyer and spinner. Providing clean and undamaged fiber is a major, world-wide problem and new methods of cleaning are urgently needed.
Foreign matter diminishes the value of the fiber because it causes processing problems and because it causes degradations of the yarn. Removal of foreign matter is always at the expense of fiber loss and fiber damage. The designer or operator of cleaning and processing equipment must, using prior art machines, make difficult and economically unattractive trade-offs between cleaning and fiber loss and damage.
Release and separation of foreign matter are important not only in processing applications. In particular, removal of foreign matter is important in instrumentation and measurement applications. Fiber properties are being determined with increasing accuracy, precision, and completeness as a consequence of new instruments for the measurements of four basic properties: length, strength, color, and fineness. Other properties and/or better ways of measuring conventional properties are under investigation. For a detailed discussion, see F. M. Shofner, W. F. Lalor, J. H. Hanley, "A New Instrument for Trash and Microdust Measurement in Raw or Processed Cotton", presented at the Natural Fibers Textile Conference, Charlotte, N.C., Sept. 14, 1982 and published under the revised title "A New Method for Microdust and Trash Measurement and Bale or Process Fiber" in Textile Research Journal, February 1983, Vol. 53, No. 2. Measurements of the above four basic properties have been automated and, with a determination of grade by a human cotton classer, have been assembled into High Volume Instrument (HVI) test lines which are increasingly used by the U.S. Department of Agriculture for setting the class of cotton, which determines its price. Thus grade is primarily influenced by foreign matter content and another urgent need exists to provide this measurement for use on HVI lines.
The present invention is concerned primarily with the bulk fiber property of foreign matter content ("trash", "dust", "microdust", respirable dust", and the like) in cotton or other fibers, and the effective removal of this foreign matter with low fiber damage and losses. Embodiments of the invention are designated "MTM", Microdust and Trash Machine. (Note: In the above-referenced Shofner at al article, MTM is used as an acronym for Microdust and Trash Monitor.)
Releasing and separating the foreign matter from the cotton permits its more accurate measurement with, for example, modern electro-optic means as described in Shofner et al U.S. Pat. No. 4,249,244. The above-referenced Shofner et al article, as well as FIG. 1 described hereinafter, generally show how electro-optical methods can be used to advantage once the foreign matter is released from the fiber and fiber and various dust components are separated into different pneumatic transport flows.
Prior art apparatus exists which cleans fiber for measurement purposes or for processing. These include the Shirley Analyzer (see "Standard Test Method for Non-Lint Content of Cotton", Designation: D 2812-81, reprinted from the Annual Book of ASTM Standard, Philadelphia, PA), as well as conventional lint-cleaning equipment which are generally effective in large particle removal. However, these machines cannot possible achieve high effectiveness in release and separation of small dust and microdust particles. They damage fiber severely if it is attempted to remove small particles with them.
Of significant importance in the context of measurement is the fact that the present invention permits release and separation and according to the following aerodynamic size classifications recently established by the International Committee on Cotton Testing Methods. (Note, AED=Aerodyanmic Equivalent Diameter.):
Trash: AED&gt;500 .mu.m PA1 Dust: 50 .mu.m&lt;AED&lt;500 .mu.m PA1 Microdust: 15 .mu.m&lt;AED&lt;50 .mu.m PA1 Respirable Dust: 0 .mu.m&lt;AED&lt;15 .mu.m PA1 Trash: AED&gt;500 .mu.m PA1 Dust: 50 .mu.m&lt;AED&lt;500 .mu.m PA1 Microdust: 0 .mu.m&lt;AED&lt;50 .mu.m
My colleagues and I have suggested in the above-referenced Shofner et al article that a slightly better terminology is:
thus making OSHA respirable dust a special case of microdust.